Arches and curves provide a beauty and eye appeal in architectural structures which is not provided by square lines. However, despite their inherent beauty, the labor intensive and time consuming task of constructing rounded structures severely limits their use. When a round staircase is built a large cylindrical wall form which will circumscribe the staircase is first fabricated. The stringers are then wrapped around this form, and the stair boards are fitted into the form with angles bolted to the wall form. Finally the wall form is removed from the stinger and stair boards; and the stair boards are fastened directly to the stringer. Considerable time and materials are utilized fabricating the cylindrical wall form and considerable time is consumed disassembling, then reassembling the stringers and stair boards after the cylindrical wall form has been removed. There is a need for a simpler, faster and less expensive method of constructing a rounded stair case.